CWD sensors for intrusion detection systems-an update

Coupled wave devices (CWDs) were developed as an alternative to leaky coaxial cables for use in perimeter guided radar detection systems. Leaky coaxial cable systems, when buried in the ground, provide a covert and all-terrain line of perimeter detection. When compared with a continuously radiating leaky coaxial cable, a CWD provides a discrete launching and reception of radio frequency (RF) "sensing" signals along a simple wire conductor. CWD sensors provide many benefits for above ground applications due to their inherent coupling efficiency, simplicity and uniform detection. Repels is the initial product that was developed based on this technology. It is a portable, rapid deployment line sensor that can be erected quickly over uneven terrain to provide a security perimeter. This paper briefly reviews the technical basis of this unique guided radar approach and discusses the technical advances. Since the introduction of the first sensor, several variations have been developed and/or introduced. S-Line and Fensor are two of these CWD-based sensors. S-Line is a permanent wall or roof-top line sensor that detects attempts at crossing an existing defined perimeter. It is able to provide detection with a single sensor over the complex three-dimensional geometry typical of a building facade. Fensor is a CWD-based sensor which provides its own inherent barrier. The perimeter detection capability of Fensor is built into an aesthetically pleasing, non-conductive fence structure suitable for new construction. Technical details, test site, and initial operational site experience for each of these alternatives are discussed.